1. Field of the Invention
The present invention relates to a polymer/liquid crystal composite, particularly, a polymer/liquid crystal composite which includes a liquid crystal material exhibiting a blue phase. The present invention also relates to a liquid crystal display device including the polymer/liquid crystal composite.
2. Description of the Related Art
As a display device which is thin and lightweight (flat panel display), a liquid crystal display device including a liquid crystal element, a display device including a self-light-emitting element, a field emission display (FED), and the like have been competitively developed.
In a liquid crystal display device, response speed of liquid crystal is required to be increased. Among various kinds of display modes of liquid crystal, liquid crystal modes capable of high-speed response are a ferroelectric liquid crystal (FLC) mode, an optically compensated bend (OCB) mode, and a mode using liquid crystal exhibiting a blue phase.
A blue phase is a liquid crystal phase which is exhibited between a chiral nematic phase having a relatively short spiral pitch and an isotropic phase, and has a feature of an extremely high response speed. A liquid crystal display device which includes a liquid crystal exhibiting a blue phase does not need an alignment film and has a wide viewing angle, and thus has been developed for practical use. However, the blue phase is exhibited only in a small temperature range of 1° C. to 3° C. between a cholesteric phase and an isotropic phase. Thus, there is a problem in that the temperature of an element needs to be controlled precisely.
In order to solve this problem, it is proposed that the temperature range where a liquid crystal material contained in a liquid crystal composition exhibits a blue phase be widened by subjecting the liquid crystal composition to polymer stabilization treatment (e.g., Patent Document 1). Specifically, Patent Document 1 discloses a technique to stabilize a blue phase of a liquid crystal material (or to expand the temperature range where a blue phase is exhibited) with a polymer (polymer network) formed by photopolymerization or thermal polymerization of monomers contained in the liquid crystal composition.